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09 May 2005 • AGE-NC Project No 97-0301 Page 2 of 6 ' 2 1 WELL MONITORING AND PURGING On 09 December 2004, depth to ground water was measured in each well from the top of the well casing to the nearest 0 01-foot utilizing a Solinst water level meter On 09 December 2004, single-completion monitoring wells MW-1 through MW-7 and multi-level monitoring wells MW-8 through MW-12 were purged by lowering and raising a 3/6-inch outer diameter, length-discrete polyethylene hose equipped with a ball-valve water tip through the top chambers into the specific water-charged screened section A Waterra Hydro-Lift II pump equipped 1 with a mechanical arm was utilized to surge each well with 3/8-inch diameter polyethylene hose Approximately 13/4 to 26 gallons of ground water (a minimum of three casing-water volumes per well)were purged from single-completion wells MW-1 through MW-7 and approximately 1/3 to 3- gallons were purged from multi-level wells MW-8 through MW-12 Temperature, pH, and conductivity were measured for stabilization at regular purge-volume intervals from each well using an Oakton water analyzer Field data and logs are included in Appendix A All purged ground water rwas transferred to Department of Transportation(DOT)-approved model 17H 55-gallon drums and stored on-site in an area lacking general public access 2 2 GROUND WATER SAMPLING After each well was purged, ground water levels were re-measured to verify the amount of ground water recharge Upon achieving at least 80% ground water recharge, samples were collected from wells MW-1 through MW-12 utilizing the techniques described above in purging each well Ground water samples from each well were transferred into three 40-milliliter(ml)EPA-approved volatile organic analysis (VOA) vials containing 0 5 ml 18% hydrochloric acid solution as a sample preservative and one 1-liter amber bottle without sample preservative Care was taken to ensure that visible air bubbles were not present in the vials after filling and capping Ground water sample containers were labeled with the well designation, date, time, and sampler's initials 1 � 2 3 LABORATORY ANALYSIS OF GROUND WATER SAMPLES Following collection and labeling,each ground water sample was logged on a chain of custody form, placed in a chilled container, and transported to Cal Tech Environmental Laboratories (CTEL), a California Department of Health Services (DHS)-certified laboratory, for analysis for • Total petroleum hydrocarbons quantified as gasoline,diesel,kerosene,and motor oil(TPH-g, ' TPH-d, TPH-k, and TPH-mo, respectively) by EPA Method 8015M, and . • Benzene, toluene, ethylbenzene, and xylenes(BTEX), methyl tertiary-butyl ether(MTBE), ' Advanced GeoEnvironmental,Inc